John E Baenziger

Professor
Deputy Chair of BMI

Degrees

B.Sc. (Hons), Queen's University (1984)
Ph.D., University of Ottawa (1989)
Post-Doctoral Fellow, Harvard Medical School and Boston University (1989-1992)

Premier's Research Excellence Award
John Charles Polanyi Prize for Doctoral Research

Contact info:

Office: Room 4216, Guindon Hall
Phone: (613) 562-5800x8222 (Office)
(613) 562-5800x8168 (Lab)
Fax: (613) 562-5251
E-mail: jebaenz@uottawa.ca

Research Interests:

There are two main research projects in my laboratory funded by grants from the Canadian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC). Both involve the structural characterization of integral membrane proteins using biophysical methods.

The first is titled "Structure and function of the nicotinic acetylcholine receptor in its membrane environment". The nicotinic acetylcholine receptor (nAChR) is a neurotransmitter-gated ion channel found at synapses located in both the nervous system and at neuromuscular junctions. The nAChR (and other homologs) plays a central role in rapid communication in the brain. Factors that influence the efficacy of synaptic communication play an important role in higher brain functions, such as memory and learning, etc. Lipids are potent modulators of nAChR function. Increasing evidence suggests that lipids play an important role modulating nAChR function under both normal and pathological conditions. The goal of this research project is to understand the mechanisms by which lipids influence nAChR function in order to ultimately understand the role of lipid-nAChR interactions in brain function in general.

The second project is titled "Structural characterization of proteins involved in iron uptake in Campylobacter jejuni”. C. jejuni is a common food borne pathogen that leads to food poisoning and in severe cases death. Like all gram negative bacteria, C. jejuni has an obligate requirement for exogenous iron and thus exhibits a complex mechanism for “stealing” iron from the human intestine. One membrane protein, called CfrA, is central to iron uptake and is a potential drug-target. We seek to understand the mechanisms by which CfrA transports iron across the outer membrane in order to develop mechanisms for inhibiting function. We are solving the crystal structure of CfrA. Using the defined crystal structure and a homology model as a guide, modern molecular biological tools are now being used to define the mechanisms of iron transport.

The laboratory is well equipped with basic biochemical equipment including Acta FPLC, cell culture incubators, a Nikon SMZ800 microscope, and a DynaPro dynamic light scatterer. There are three modern FTIR spectrometers, including a new FTS 7000 from Varian. These are equipped with numerous FTIR data acquisition accessories, including standard ATR sampling accessories, a Golden Gate diamond ATR, and both manual and automated polarizers. The FTIR systems have been fully automated for measuring difference and absorbance spectra as a function of both light polarization and temperature. The lab is also equipped with a Cary Eclipse fluoresence spectrometer. We have access to electrophysiological equipment.

Grant Support:

Canadian Institutes of Health Research
Natural Sciences and Engineering Research Council of Canada

Administrative Positions:

Chair of Undergraduate Biochemistry (2004-2011)
Member of Editorial Board for the Journal of Biological Chemistry (2003-2008)
Scientific Officer, BMA grant review panel for CIHR (2000, 2004-2008)
Regular member, BMA grant review panel for CIHR (1997-2000)

Recent Publications:

J.E. Baenziger & P.J. Corringer “3D structure and allosteric modulation of the transmembrane domain of pentameric ligand-gated ion channels” Neuropharmacology (2011) 60, 116-125
J.M. Labriola, C.J.B. daCosta, S. Wang, D. Figeys, J.C. Smith, R.M. Sturgeon, & J.E. Baenziger “Phosphatidic acid-specific phospholipase C activity affinity purifies with the Torpedo nicotinic acetylcholine receptor” J. Biol. Chem. (2010) 285, 10337-10343
R.M Sturgeon & J.E Baenziger “Cations mediate interactions between the acetylcholine receptor and anionic lipids” Biophys J. 98, 989-998
C.J.B. daCosta, S.A. Medaglia, N. Lavigne, S. Wang, C.L. Carswell & J.E. Baenziger “Anionic lipids allosterically modulate multiple acetylcholine receptor conformational equilibria” J. Biol. Chem. (2009) 284: 33841-33849
N. Vuong, J.E. Baenziger & L.J. Johnston “Preparation of reconstituted acetylcholine receptor membranes suitable for AFM imaging of lipid-protein interactions” Chem. Phys. Lipids (2010) 163, 117-126.
C.J.B. daCosta, & J.E. Baenziger “A lipid-dependent uncoupled conformation of the acetylcholine receptor” J. Biol. Chem. (2009) 284: 17819-17825.
W.M. Sayeed & J.E. Baenziger “Structural characterization of the osmosensor ProP” Biochim. Biophys. Acta. (2009) 1788:1108-15.
S.D. Ryan, C.S. Harris, C.L. Carswell, J.E. Baenziger, & S.A. Bennet “Heterogeneity in the sn-1 carbon chain of platelet activating factor glycerophospholipids determines pro-or anti-apoptotic signaling in primary neurons” J. Lipid Res. (2008) 49:2250-8
C.L. Carswell, M.D. Rigden and J.E. Baenziger “Expression, Purification and Structural Characterization of CfrA, a Putative Iron Transporter from Campylobacter jejuni” J. Bact. (2008) 190:5650-62
J.E. Baenziger, S.E. Ryan, M.M. Goodried, N.Q. Vuong, R.M. Sturgeon, & C.J.B. daCosta “Lipid composition alters drug action at the nicotinic acetylcholine receptor” Mol. Pharmacol. (2008) 73:880-90.
J.E. Baenziger & C.J.B. daCosta “Membrane Protein Structure and Conformational Change probed using Fourier Transform Infrared Spectroscopy” in Biophysical Analysis of Membrane Proteins. Investigating Structure and Function” (Pebay-Peyroula, ed.) 2008 pp 259-288, Wiley-VCH. Weinheim, Germany.
D.G. Hill & J.E. Baenziger “The net orientation of nicotinic receptor transmembrane alpha-helices in the resting and desensitized states” Biophys. J. (2006) 91: 705-14.
J.E. Baenziger, S.E. Ryan, & V.C. Kane-Dickson "Membrane Receptor-Ligand Interactions Probed by Attenuated Total Reflection Infrared Difference Spectroscopy" in Vibrational Spectroscopy of Biological and Polymeric Materials (M. Braiman and V. Gregoriou, eds.) 2006 pp 325-352, CRC Press, Boca Raton, FL.